IC tray handling apparatus and method

ABSTRACT

A microchip tray handling apparatus has microchip loading and receiving units for supplying microchips to a microchip tester and receiving tested microchips. The units have tables to support stacks of trays containing microchips. Each unit has a tray holding assembly for raising a stack of trays to allow a bottom tray to allow a bottom tray to be moved along the table. Pick, invert and place probes remove microchips from the trays and place tested microchips back into the trays.

FIELD OF THE INVENTION

The invention relates to article handling apparatus operable to dispenseand receive articles normally stored in packaging structures. Thearticle handling apparatus handles trays storing microchips which areremoved from the trays for testing and returned to the trays after thetesting is completed.

BACKGROUND OF THE INVENTION

Computer IC chips called microchips must be tested for operability,efficiency and environmental compatibility after they are manufactured.Machines that automate such testing have been developed to reduce theamount of labor required to perform tests on relatively smallmicrochips. Microchips are stored in generally rectangular trays whichprotect the microchips during transport from the manufacturer to thetesting location and to the final assembly place. The microchips areindividually tested apart from their storage trays. The trays aremanually placed in tray handling devices having automated structuresthat remove each microchip from the tray and place the microchip on abelt which delivers the microchips to a testing machine. Probes andinverting devices have been developed to pick up microchips from thetrays and place them in a desired location, such as a belt which movethe microchips to a testing machine. An example of a probe and invertingdevice is shown in U.S. Pat. No. 5,201,875. The loading and unloading ofthe trays into and from the tray handling devices is a tediouslyrepetitive manual operation which subjects the hand, wrists and arms ofpersonnel to stresses and strains.

SUMMARY OF THE INVENTION

The invention is directed to an integrated circuit, IC, tray handlingapparatus and method that accommodates a stack of trays holdingmicrochips and functions to separately remove microchips from a trayonto a moving belt for delivery to a microchip tester. The entire stackof trays is quickly and easily loaded from the end of the tray handlingmechanism of the apparatus. The efficient handling of the stack of traysalso reduces strains and stresses on the hands, wrists and arms ofpersonnel handling the stack of trays.

The apparatus has a loading tray unit and receiving tray units. Theloading unit accommodates a stack of trays having microchips. The bottomtray is moved from a first position to a second position on a tablewhere the microchips are picked up and transferred onto a belt thatdelivers the microchips in sequence to an IC tester. A second belt movesthe tested microchips from the IC tester. A second microchip pick up andtransfer mechanism individually picks up the microchips and places themin empty trays. Rejected microchips are placed in a tray separate fromthe acceptable microchips. The microchip loading and receiving unitshave tray holders connected to lift structures that selectively move theholders in an upward direction so as to raise the stack of trays abovethe bottom tray so that the bottom tray can be moved in a forwarddirection allowing the microchips in the bottom tray to be picked up,inverted and transferred to the belt that delivers the microchips to theIC tester or pick up microchips from the belt that dispenses microchipsfrom the IC tester depositing the microchips back into a tray.

The preferred embodiment of the apparatus for handling and stackingtrays holding microchips has a generally horizontal table for supportingtrays. Ribs secured to the table provide guides for the trays as theymove along the table. Upright posts mounted on the table adjacent theribs have inwardly directed lips providing stops for the stack of traysand locate the trays in a first position on the table. The ribs andposts do not interfere with the horizontal loading of the stack of trayson the table. A tray handling assembly operates to lift the stack oftrays except the bottom tray so that the bottom tray can be moved to asecond position where the microchips are picked up from the tray,inverted and deposited onto a belt for delivery to a microchip tester.The tray holding assembly has upright holders or members having movablepawls that engage opposite sides of a tray so as to lift the stack oftrays and subsequently lower the trays back on the table. The holdersextend through holes in the table and are mounted on a plate locatedbelow the table. The plate is selectively moved up and down with leadscrews driven by an electric motor. The screws are threaded throughsleeves mounted on the plate so that rotation of the screws moves theplate and holders mounted thereon. A tray moving device having acarriage movably mounted on rails below the table and a finger adaptedto engage the bottom tray operates to move the bottom tray from thefirst position to a second position.

A microchip pick up, transfer and place mechanism has vacuum suctioncups connected to air cylinders operable to pick up a microchip from thetray, invert the microchip and place the microchip on a belt fordelivery to a microchip tester. This procedure is continued until all ofthe microchips are removed from the tray. The tray moving device thenmoves the empty tray to a third position into engagement with end stopson the table. The empty tray is elevated with a second tray holdingassembly having holders that engage opposite sides of the tray.

A tray transfer mechanism picks up the empty tray and moves it to amicrochip receiving unit. A second microchip pick up, transfer and placemechanism picks up microchips from a belt carrying tested microchipsfrom the tester, inverts the microchips and places the microchips in atray located on a table of the receiving unit. Rejected microchips aredeposited in separate trays located on a second receiving unit. Thereceiving units have tray moving devices that move the trays from themicrochip loading position to a stacking position on the table. A trayholding assembly elevates the stack of trays so that a new tray can beplaced under the stack of trays. The tray holding assembly operates inthe same manner as the tray holding assembly in the loading unit. Theentire stack of trays on the receiving unit is manually removed from theunit after a selected member of trays accommodating tested microchipshave been stacked on the receiving unit. The stack of trays are movedhorizontally from the table in an efficient manner that minimizesstresses and strains on the hands, wrists and arms of persons handlingthe trays.

A method of handling trays is included in the invention. A stack oftrays holding microchips is loaded on a table in a first position. Thestack of trays is moved in a general longitudinal and horizontaldirection to reduce stresses and strains on the hands, wrists and armsof persons performing the loading procedure. The stack of trays on thetable, with the exception of the bottom tray, is elevated to allow thebottom tray to be moved to a second microchip unloading position. Themicrochips are picked up one at a time from the tray, inverted andplaced on a belt. The belt delivers the microchips to an IC tester.After all of the microchips have been removed from the tray, the tray ismoved to a third empty position. The empty tray is transferred to amicrochip receiving unit. Microchips from the IC tester are loaded onthe tray with a pick up, invert and place mechanism. The tray containingthe tested microchips is stacked and then removed from the receivingunit.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagrammatic plan view of the IC tray handling apparatus ofthe invention associated with an IC tester;

FIG. 2 is a diagrammatic view of the mechanism for unloading microchipsfrom a tray and placing the microchips on a belt of the apparatus ofFIG. 1;

FIG. 3 is a diagrammatic view of the mechanism for picking up microchipsfrom a belt and loading the microchips on a tray of the apparatus ofFIG. 1;

FIG. 4 is a diagrammatic view of the tray transfer mechanism of theapparatus of FIG. 1;

FIG. 5 is a top plan view of a tray handling unit of the apparatus ofFIG. 1;

FIG. 6 is an enlarged sectional view taken along the line 6--6 of FIG.5;

FIG. 7 is a side elevational view of the tray handling unit of FIG. 5;

FIG. 8 is an enlarged sectional view taken along the line 8--8 of FIG.5;

FIG. 9 is an end view of the inlet end of the tray handling unit of FIG.5;

FIG. 10 is an enlarged sectional view taken along the line 10--10 ofFIG. 5 showing the tray holders in the down position;

FIG. 11 is a sectional view similar to FIG. 10 showing the tray holdersin the up position;

FIG. 12 is a bottom plan view of the tray handling unit of FIG. 5;

FIG. 13 is an enlarged sectional view taken along the line 13--13 ofFIG. 12;

FIG. 14 is an enlarged sectional view taken along the line 14--14 ofFIG. 5; and

FIG. 15 is a sectional view taken along the line 15--15 of FIG. 10.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, there is shown a diagrammatic view of the IC trayhandling apparatus of the invention indicated generally at 10. The term"IC" refers to integrated circuit flat packages called microchips. Thetray handling apparatus 10 operates to supply microchips in sequence toan IC tester 11 and receive the tested microchips from the IC tester 11and return the microchips to selected trays. The trays are generallyflat, rectangular structures having a plurality of pockets thataccommodate microchips. An example of a tray for microchips is shown inIBM Technical Disclosure Bulletin No. 110112 dated March, 1991.

Apparatus 10 has a first movable belt 12 for receiving microchips 13from a loading unit 19 and moving the microchips in the direction ofarrow 14 into IC tester 11. Upon completion of the testing of themicrochips for both mechanical and electrical characteristics undervarious thermal environments, the microchips are moved out of tester 11on a second belt 16. The tested microchips 17 move in the direction ofarrow 18 and are placed selectively on trays 52 and 61 retained inreceiving units, indicated generally at 20 and 21.

Loading unit 19 accommodates a stack of trays 22 containing microchipsto be tested. The stack of trays 22 can be quickly and easily loadedfrom the end of loading unit 19 with a minimum of strain and stress onthe hands, wrist and arm of the person's handling the stack of trays.The method and structure used to load the stack of trays is ergo or workefficient.

Loading unit 19 is operable to move the bottom tray 23 of the stack oftrays to a location where microchips are selectively picked up from thetray and placed on belt 12 with a pick up and transfer mechanism,indicated generally at 24. As shown in FIG. 2, mechanism 24 has a firstunit 26 comprising an air cylinder 27 attached to a vacuum suction cup28. Air cylinder 28 is rotatably mounted on a stepping motor 29 operableto move the cylinder 27 from a generally vertical position to ahorizontal position. When cylinder 27 is in the vertical position, thesuction cup 28 is moved down to place microchip 13 on belt 12 when thevacuum on suction cup 28 is released. Mechanism 24 has a second unit 31comprising an air cylinder 32 operatively associated with a vacuumsuction cup 33. Air cylinder 32 is operable to move suction cup 33 in adownward direction. A vacuum applied to cup 33 picks up microchip 34from tray 23. A stepping motor 36, connected to cylinder 32, is operableto rotate cylinder 32 into a horizontal position in general alignmentwith cylinder 27. Microchip 34 is then transferred to suction cup 28 byreleasing the vacuum on cup 33 and applying vacuum to cup 28. Cylinder27 is then moved to the vertical position, as shown in full lines inFIG. 2, whereby suction cup 27 is then lowered and the vacuum thereonreleased to place the microchip on belt 12. Stepping motor 36 islaterally moved with a lead screw 37 driven by an electric motor 38. Themotor 38 is a reversible motor whereby the stepping motor 36 moves inopposite directions, indicated by arrow 39. This laterally moves aircylinder 32 and suction cup 33 so that it can pick up the laterallylocated microchips on tray 23. Tray 23 has a plurality of rows ofpockets accommodating microchips which are picked up one at a time bysuction cup 33. The outwardly directed leads on microchip 34 in tray 23are directed in a downward direction to protect the leads from damage.The pick up and transfer mechanism 24 inverts the microchips on belt 12whereby the leads are directed in an upward direction.

A second microchip pick up and transfer unit, indicated generally at 41in FIG. 3, has a first pick up unit 42 operable to pick up a microchip17 from belt 16 and move the microchip in a generally horizontallocation where it is transferred to a second receiving and depositingunit, indicated generally at 47. First pick up unit 42 has an aircylinder 43 connected to a vacuum suction cup 44. A stepping motor 46 isused to rotate the air cylinder 43 from a generally vertical position toa horizontal position. Second receiving and depositing unit 47 has anair cylinder 48 connected to a vacuum suction cup 49. Suction cup 49 isoperable to receive the microchip from suction cup 44 and move themicrochip to a generally horizontal position adjacent tray 52. Microchip51 is then placed on the tray 52. Air cylinder 48 is moved with theoperation of a stepping motor 53. Stepping motor 53 is movably mountedon a generally horizontal rail 54 for lateral movement to allow rejectedmicrochips to be placed in a second tray 61. An endless chain drive 56,connected to stepping motor 53, is driven by an electric motor 57. Thevalves (not shown) for controlling the air and vacuum supply to aircylinders 27, 32, 43 and 48 and vacuum suction cups 28, 34, 44 and 49,as well as the electric power to the stepping motors 29, 36, 46, and 53and, the lateral drive motors 38 and 57 are controlled with a computercontrol 58 and computer program incorporated therein.

Referring to FIG. 4, there is shown the tray transfer device, indicatedgenerally at 59, for laterally moving the empty trays from loading unit19 to one of receiving units 20 and 21. When tray 23, in loading unit 19is empty, the tray transfer device 59 picks up the tray and moves itlaterally to either the receiving unit 20 or receiving unit 21.Microchips are then reloaded onto the trays in the receiving units 20and 21 with the approved microchips being loaded on receiving unit 20and the rejected microchips being loaded in the tray 61 on receivingunit 21. Tray transfer device 59 has a carriage 62 that is movablymounted on a transverse rail 63 located above the rear portions of theloading unit 19 and receiving units 20 and 21. Carriage 62 is laterallymoved along rail 63 with an endless cable or cord 64, driveablyconnected to a reversible electric motor 66, as indicated by arrow 67.Other structures, such as lead screws, can be used to move carriage 62along rail 63. A downwardly-opened yolk 68, having pick up pads 69 and71, is adapted to grip opposite sides of a tray. Pads 69 and 71 can beexpandable members that operate in response to air pressure to gripopposite sides of the tray. Movable gripping pawls can be used in lieuof pads 69 and 71 to pick up the empty trays and deposit the empty trayson one of the receiving units 20 or 21. The empty trays are verticallymoved upwardly by the second tray lift members or holders, hereinafterdescribed. The top tray is moved up into yolk 68 and is retainedtherein. The remaining empty trays are lowered and the carriage 62 movedalong rail 63 to relocate the empty tray on one of the receiving units20 or 21. Other structures can be used to move the empty trays fromloading unit 19 to receiving units 20 and 21.

Referring to FIGS. 5, 7 and 9, loading unit 19 has a flat top table 79with a longitudinal middle slot 81. Opposite flat side walls 82 and 83are joined to opposite longitudinal edges of table top 79 to supporttable 79 above a fixed surface. A pair of longitudinal guides or ribs 84and 86 are secured to the top of table 79 with a plurality of bolts 87,as seen in FIG. 8. Ribs 84 and 86 are linear parallel members laterallyspaced from each other. The lateral or transverse space between ribs 84and 86 is slightly greater than the width of a tray so that the bottomtray is free to move longitudinally along table 79. Ribs 84 and 86 haveinwardly-directed beveled edges 88 to facilitate the insertion of astack of trays 22 on top table 79. A pair of upright posts 89 and 92 areattached to table 79 with blocks 94 and 96. Post 89 has aninwardly-directed lip 91 which is aligned with an inwardly-directed lip93 on post 92. The lips 91 and 93 serve as stops for positioning thelongitudinal location of the stack of trays 22 on top of table 79. Asseen in FIG. 9, the bottom edges of lips 91 and 93 are spaced above thetop of table 79 to allow a bottom tray to be moved along table 79 in aforward direction toward rear stops 134 and 136. The upright insidewalls of posts 89 and 92 provide lateral upright guide surfaces for thestack of trays 22. The stack of trays 22 are merely placed on the top oftable 79 between ribs 84 and 86 with the forward ends of the stack oftrays 22 in engagement with lips 91 and 93. The entire stack of trays 22is quickly and easily loaded with generally horizontal motion from theend of the loading unit 19, as there are no structures that interferewith the horizontal movement of the stack of trays 22 as they are movedinto engagement with lips 91 and 93. Vertical lifting and subsequentdropping of the stack of trays is not required to place the trays on theloading unit. This substantially reduces the strain and stress on thehands, wrists and arms of personnel handling the stack of trays 22.

Referring to FIGS. 10 and 11, tray handling apparatus 10 has a trayholding assembly, indicated generally at 97, operable to lift the stackof trays 22, leaving the bottom tray on table 79. When the bottom trayhas been moved forward to the empty tray location, the tray holdingassembly 97 will lower the stack of trays 22 so that another bottom traycan be unloaded. When the empty tray is in the empty tray location it isin engagement with end stops 134 and 136.

Tray holding assembly 97 has a generally horizontal plate 98 locatedbelow table 79. Four upright members or holders 99, 100, 101 and 102 areattached to plate 98 with a plurality of bolts 106 and 107. Uprightmembers 99 and 100 extend through holes 103 and 104 in table 79. Uprightmembers 101 and 102 extend through similar holes in table 79. As seen inFIG. 5, upright members 99 and 101 are aligned with rail 84 so as not tointerfere with the loading of the stack of trays 22 onto the top oftable 79. Upright members 101 and 102 are aligned with rail 86 so as tonot interfere with the location of the stack of trays 22 onto the top oftable 79.

Referring to FIG. 14, upright member 100 has a recess 112 accommodatinga pawl 108. Pawl 108 has an inwardly-directed lip 109 adapted to engagethe side of a tray. A pivot pin 111 pivotally connects pawl 108 toupright member 100 to allow lip 109 to move into recess 112 whereby thepawl can move past the bottom tray of the stack of trays 22. An aircylinder 113 interposed between the upright member 100 and pawl 108functions to control the position of pawl 108. A fluid line 114 connectsthe air cylinder 113 to a source of fluid under pressure and a valvingstructure (not shown) to control the operation of fluid cylinder 113.Each of the upright members 99, 100, 101 and 102 has a similar pawlwhich engages an adjacent side of a tray, as seen in FIG. 11.

Plate 98 is supported on four upright lead screws 114, 115, 116 and 117.Rotation of the lead screws causes plate 98 to selectively move up anddown thereby moving the upright members 99-102 from a lower position toan upper position to raise the stack of trays 22 above the bottom trayand subsequently return from an upper position to a lower position, asseen in FIG. 10.

Referring to FIG. 13, there is shown a detailed structure of lead screw117 and its operative association with plate 98. Lead screws 115, 116and 117 have the same structure. An upper support block 118 secured tothe side wall 82 has a roller bearing 119 accommodating the upper end oflead screw 117. A similar support block 120 is secured to the lower sideof side wall 82 and accommodates a roller bearing 121 for the lower endof lead screw 117. A sleeve 122 has internal threads that accommodatethe threads of lead screw 117. Sleeve 122 extends through a hole 123 inplate 98 and is secured thereto with bolts 124. Sleeve 122 projectsupwardly from the top of plate 98 and is adapted to engage the uppersupport block 118 when plate 98 is in its up position. A gear 126,secured to the lower end of lead screw 117, accommodates an endless belt131. As seen in FIG. 12, belt 131 is trained about gears 127,128 and 129attached to the lead screws on the corners of plate 98. Belt 131 istrained about a drive gear 132 which is attached to a reversibleelectric motor 133, such as a stepping motor. Motor 133 is operable tomove belt 131 thereby simultaneously rotating the lead screws 114, 115,116 and 117 to selectively raise and lower plate 98. Holders 99-101 movein opposite vertical directions to raise and hold the stack of traysduring the unloading of microchips from the bottom tray.

Returning to FIG. 5, loading unit 19 has a pair of rear stops 134 and136 mounted on top of table 79. Stops 134 and 136 determine the emptytray position of the tray on table 79. Upright members or holders 137,138, 139 and 140 are located along ribs 84 and 86 on opposite sides ofthe tray and are operable to raise a stack of empty trays up in anupward direction to allow another empty tray to be moved toward stops134 and 136. The top tray is moved up into yolk 68 so that it can betransported to one of receiving units 20 or 21. Holders 137, 138, 139and 140 are mounted on a generally horizontal plate which is selectivelyraised and lowered with lead screws, such as plate 98 and lead screws114, 115, 116 and 117, as shown in FIGS. 10 and 11. Computer control 58regulates the operation holders 137-140.

Referring to FIG. 6, there is shown a tray moving mechanism, indicatedgenerally at 141, for moving the bottom tray from its initial loadposition to the unload position generally in the middle of table 79 andthe empty tray position adjacent the rear stops 136 and 137. The traymoving mechanism 141 is mounted on a pair of longitudinal rails 142 and143 located below the top of table 79 adjacent opposite sides of theslot 81. A carriage 144, having rollers 146 and 147, is movably mountedon rails 142 and 143. A finger 148, having an upright end 149, locatedwithin slot 81, is connected with a pivot 151 to carriage 144. An aircylinder 152 mounted on carriage 144 has an upright piston rod 153connected with a pivot 154 to finger 148 whereby operation of aircylinder 152 causes the finger to pivot in an upward direction to movethe end 149 of the finger adjacent the back of tray 23. Air cylinder 152is also operable to retract finger 148 below the top of table 79 so thattray moving mechanism 141 can be moved back to its original positionwithout affecting the stack of trays 22. A reversible electric motor156, such as a stepping motor, is operably connected to a cable andpulley structure 157 that is joined to carriage 144 so that carriage 144can be reciprocated below the top of table 79 to selectively move bottomtray 21 in a forward direction during the unloading of the microchipsfrom the tray. Bottom tray 21 is moved step by step to align a row ofmicrochips with microchip pick up and transfer mechanism 24. When all ofthe microchips in a row of microchips have been removed, the tray ismoved forward so that a second row of microchips can be removed from thetray. The empty tray is moved forward to the empty tray position andanother tray is moved forward to the unload position.

The microchips receiving units 20 and 21 have the same structure asloading unit 19. The parts of unit 20 that correspond to the parts ofunit 19 have the same reference numbers with the suffix A. The parts ofunit 21 that correspond to the parts of unit 19 have the same referencenumbers with the suffix B. This structure includes the tray movingmechanism shown in FIG. 6 and the tray holding assembly shown in FIGS.10, 11, 13, 14 and 15. The tray moving mechanism of receiving unit 20has an upright finger 160 that is adapted to engage the forward end ofthe empty tray and move the tray in an outward direction along the topof the table. The receiving unit 21 has a similar finger 170 associatedwith the tray moving mechanism that moves the tray in an outwarddirection along the table. The trays are sequentially moved to presentopen pockets for receiving microchips. When the tray is full ofmicrochips, it is moved with the tray moving mechanism to the unloadingposition. The tray holding mechanism stacks the trays on the front ofthe receiving units 20 and 21. The stacks of trays can be convenientlyremoved from the units 20 and 21 by gripping opposite sides of the traysand longitudinally pulling the trays off of table 79. This is anefficient method of handling the stack of trays which reduces strainsand stresses on the hands, wrists and arms of personnel that move thestack of trays.

In use, the operator places a stack of trays 22 onto the loading unit19. The trays are placed between the longitudinal ribs 84 and 86 intoengagement with upright posts 89 and 92. The tray holders 99, 100, 101and 102 are then lifted to raise the stack of trays, except the bottomtray, above table 79. The tray moving mechanism 141 is then operable tomove the bottom tray in a forward direction thereby exposing the rows ofmicrochips to the unloading location. The pick up and transfer mechanism24 is then operated to pick up microchips from the tray and place themon belt 12. The microchips move along belt 12 into the IC tester wherethey are tested in accordance with the testing parameters of tester 11.When tray 23 is empty, it is moved into the full empty position intoengagement with the end stops 134 and 136. The tray moving mechanism 141is then moved back to the original position where it can pick up asecond tray. The tray holders 99, 100, 101 and 102 are then lowered toplace the next tray on table 79. The tray holders 99, 100, 101 and 102are then elevated to lift the stack of trays, except the bottom tray.The tray moving mechanism 141 is then moved forward to the unloadingposition to expose microchips to the pick up and transfer mechanism 24.Mechanism 24 operates to unload the microchips from the tray and placethem on belt 12 which moves the microchip into IC tester 11.

The tray transfer device 59 is used to move the empty tray from theloading device 19 and place the empty tray on one of the receivingdevices 20 or 21.

The second pick up and transfer unit 41 operates to pick up testedmicrochips 17 from belt 16 and deposit the microchips into trays 52 or61 on receiving units 20 and 21. The tray moving mechanism with itsfinger 160 operates to move tray 52 in the forward direction and underthe trays in the unloading location. The tray holders of the receivingunit are used to sequentially elevate the trays thereby stacking thetrays in the receiving unit. The receiving unit 21 operates in the samemanner as receiving unit 20.

While there is shown and described a preferred embodiment of theapparatus and method for handling IC trays, it is understood thatchanges in the structure, arrangement of structure, parts and method maybe made by those skilled in the art without departing from theinvention. The invention is defined in the following claims.

I claim:
 1. An apparatus for handling trays accommodating microchipscomprising: a generally horizontal table for supporting a plurality oftrays holding microchips, rib means secured to the table for locatingthe trays on the table and guiding one tray along the table, uprightpost means mounted on the table engageable with the trays to locate astack of trays on the table in a first position, tray handling means forlifting the stack of trays, except the bottom one tray, supported on thetable, first means operable to move the one tray on the table from thefirst position to a second position, second means for removingmicrochips from the one tray and placing the microchips in a selectedlocation, said first means being operable to move the one tray from thesecond position to a third position on the table when all of themicrochips have been removed from the one tray, said tray handling meansbeing operable to lower the stack of trays on the table and subsequentlyraise the stacks of trays leaving a second bottom tray on the table,said first means being operable to move the second bottom tray from thefirst position to the second position so that microchips can be removedfrom the second bottom tray.
 2. The apparatus of claim 1 wherein: thetable includes a longitudinal slot, said first means being located belowsaid table and having a finger movable through said slot into engagementwith a bottom tray whereby the first means moves the bottom tray alongsaid table.
 3. The apparatus of claim 1 including: longitudinal trackmeans located below said table, said table having a longitudinal slot,said first means includes carriage means movably mounted on the trackmeans, finger means pivotally mounted on the carriage means, said fingermeans having an end movable through said slot into engagement with abottom tray, means mounted on the carriage means operable to pivot thefinger means to move the end relative to said slot whereby said endselectively is located above the table and below the table, and meansfor moving the carriage means along the track means thereby moving thebottom tray from the first position to the second position and from thesecond position to the third position.
 4. The apparatus of claim 1wherein: the rib means includes a first longitudinal rib and a secondlongitudinal rib located generally parallel to the first rib, said firstand second ribs being laterally spaced from each other to accommodate atray.
 5. The apparatus of claim 4 wherein: the upright post meansincludes a first post aligned with the first rib and a second postaligned with the second rib, said first and second posts each having aninwardly directed lip engageable with the trays to locate a stack oftrays on the table in said first position, each lip having a lower edgespaced above the table to allow a bottom tray to move under the lip fromthe first position to the second position.
 6. The apparatus of claim 1wherein: the tray handling means includes upright members extendedthrough holes in said table adjacent opposite sides of the bottom onetray located in the first position, said upright members having meansengageable with the trays operable to lift the stack of trays except thebottom one tray when the upright members are moved in an uprightdirection, and means connected to the upright members operable toselectively move the upright members in up and down directions.
 7. Theapparatus of claim 6 wherein: the means engageable with the trays arepawls movably mounted on the upright members, and devices to move thepawls to a first position for engagement with a tray and to a secondposition wherein the pawl does not engage the tray.
 8. The apparatus ofclaim 6 wherein: the means connected to the upright members comprise aplate located below the table, and power means operatively connected tothe plate for moving the plate in up and down directions.
 9. Theapparatus of claim 8 wherein: the power means includes lead screws,sleeves mounted on the plate accommodating the lead screws and drivemeans for rotating the lead screws thereby moving the plate selectivelyin up and down directions.
 10. An apparatus for handling traysaccommodating microchips comprising: a table having an end and a topsurface for supporting trays for storing microchips, rib means connectedto the table for positioning a stack of trays on said table top surface,said rib means comprising a pair of longitudinal ribs secured to the topsurface of the table, said ribs being laterally spaced from each otherto accommodate a bottom tray to allow longitudinal movement of thebottom tray and guide the bottom tray relative to the top surface of thetable, upright stop means mounted on the table adjacent the rib meansinwardly from said end of the table whereby a stack of trays can behorizontally loaded onto said table from the end of the table in a firstposition, tray holding means for lifting the stack of trays, except abottom tray, tray moving means for moving the bottom tray from the firstposition along said surface of the table past the stop means to a secondposition allowing microchips to be removed from the tray, said trayholding means being operable to lower the stack of trays on the tableand subsequently raise the stack of trays leaving a second bottom trayon the table, said moving means being operable to move the second bottomtray from the first position to the second position so that microchipscan be removed from the second bottom tray.
 11. The apparatus of claim10 wherein: the upright stop means has at least one inwardly directedlip, said lip having a lower edge spaced above the table to allow abottom tray to move under the lip from the first position to the secondposition.
 12. The apparatus of claim 10 wherein: said upright stop meansincluding a first post aligned with the first rib and a second postaligned with the second rib, each post having an inwardly directed lip,and each lip having a lower edge spaced above the table to allow abottom tray to move under the lip from the first position to the secondposition.
 13. The apparatus of claim 10 wherein: the table includes alongitudinal slot, said tray moving means being located below said tableand having a finger movable through said slot for engagement with thebottom tray whereby the tray moving mans operates to move the bottomtray from the first position to the second position.
 14. The apparatusof claim 10 wherein: the tray holding means includes upright membersextended through holes in said table adjacent opposite sides of thebottom tray located in the first position, said upright members havingmeans engageable with the trays operable to lift the stack of traysexcept the bottom tray when the upright members are moved in an uprightdirection, and means connected to the upright members operable toselectively move the upright members in up and down directions.
 15. Theapparatus of claim 14 wherein: the means engageable with the trays arepawls movably mounted on the upright members, and devices to move thepawls to a first position for engagement with a tray and to a secondposition wherein the pawl does not engage the tray.
 16. The apparatus ofclaim 14 wherein: the means connected to the upright members comprise aplate located below the table, and power means operatively connected tothe plate for moving the plate in up and down directions.
 17. Theapparatus of claim 16 wherein: the power means includes lead screws,sleeves mounted on the plate accommodating the lead screws and drivemeans for rotating the lead screws thereby moving the plate selectivelyin up and down directions.
 18. An apparatus for handling traysaccommodating microchips comprising: a table having an end and a topsurface for supporting trays for storing microchips, rib means connectedto the table for positioning a stack of trays on said table top surface,upright stop means mounted on the table adjacent the rib means inwardlyfrom said end of the table whereby a stack of trays can be horizontallyloaded onto said table from the end of the table in a first position,tray holding means for lifting the stack of trays, except a bottom tray,tray moving means for moving the bottom tray along said surface of thetable past the stop means to a second position allowing microchips to beremoved from the tray, said tray holding means being operable to lowerthe stack of trays on the table and subsequently raise the stack oftrays leaving a second bottom tray on the table, said tray moving meansbeing operable to move the second bottom tray from the first position tothe second position so that microchips can be removed from the secondbottom tray, longitudinal track means located below said table, saidtable having a longitudinal slot, said tray moving means includescarriage means movably mounted on the track means, finger meanspivotally mounted on the carriage means, said finger means having an endmovable through said slot into engagement with a bottom tray, meansmounted on the carriage means operable to pivot the finger means to movethe end relative to said slot whereby said end selectively is locatedabove the table and below the table, and means for moving the bottomtray from the first position to the second position and from the secondposition to the third position.